The disclosure relates in general to a protection circuit, and in particular to a protection circuit for voltage overload.
Voltage sources deliver current to electronic device, normally through a transformer. For safety, an protection circuit between the voltage source and the electronic device safeguards abnormal power supply, preventing damage.
FIG. 1 is a block diagram of a electronic system with an protection circuit. The system comprises a voltage source 10, an protection circuit 12, a transformer 15, and a load 16. Protection circuit 12 incorporates a breaking circuit 121 and a detection feedback circuit 122. Transformer 15 comprises a primary winding 151 coupled to voltage source 10 via a breaking circuit 121, and a secondary winding 152 coupled to load 16 and a detection feedback circuit 122. Load 16 may be any type of electronic device, such as a light tube. Load 16 is coupled to ground. Detection feedback circuit 122 is further coupled to breaking circuit 121, and detects abnormal voltage at secondary winding 152. If the voltage at secondary winding 152 renders an abnormal value, i.e. output voltage exceeds a predetermined value, the detection circuit 122 generates a signal, such that breaking circuit 121 interrupts the circuit.
Protection circuit 12 does not restore breaking circuit 121, nor does it resume operation of load 16, despite the voltage returning to normal. This imposes a design limitation to the applications. As a compensation a restore circuit is incorporated into the circuitry, results in more complex circuitry, increased component count, and manufacturing cost increases.
Thus an protection circuit is in need, providing over voltage protection upon abnormal voltage detection, and power supply restoration under normal condition.